1. Field of the Invention
Present invention is directed to a method for forming a film-covered article. More specifically, the present invention is directed to providing a method of forming a perforated tear seam along a perimeter of a film to remove an offal portion from the molded article.
2. Description of the Related Arts
It is also known to manufacture molded articles using flexible films wherein the film is placed within a mold and a polymer is injected behind the film to heat and soften the film backing. The film backing fuses to the polymer to form a molded article. One difficulty of this construction is that it generally produces an edge of film or fabric that must be either trimmed or folded to present a neat appearance. One example of edge trimming is illustrated in commonly assigned U.S. patent application Ser. No. 08/903,523, titled: "METHOD AND APPARATUS FOR MANUFACTURING A FILM-COVERED ARTICLE". This application teaches a method and apparatus for trimming a film placed between two molds. The offal portion of the film is cut by shear edges on the mold. The offal portion is separated from the film and must be separately removed from the mold press.
In highly automated injection molding presses, the area between the molds is generally inaccessible to the machine operator. By separating the offal portion from the film, the offal portion must be removed independently from the finished part. Because the offal portion is generally thin and irregularly shaped, it is difficult to design robotically controlled equipment to remove the offal portion from between the molds. It is desirable for the offal portion to remain attached to the finished article for easy removal at a location remote from the mold press.
Another method of producing a film-covered article is illustrated in U.S. Pat. No. 5,599,608. A flat film sheet is thermoformed to have an in-turned portion. The film is trimmed to the final desired measurement and is then placed within a molding apparatus. The mold core engages the in-turned portion and folds the edge of the film within the mold. Molten plastic is injected into the mold cavity and the combination of closing the mold combined with the pressure of the molten plastic material forces the in-turned edge portion against the mold wall to form the covered edge of the molded article.
This method requires a complicated pre-molding operation that thermoforms the film to have an in-turned portion and then trims the film prior to placing the film within the mold. The film has only a small in-turned portion that must lie within the mold and may not be used to properly position the film within the mold or retain the film while the mold is closed. Because the film is totally encased between the mold halves, it may not be used to seal the space between the molds.
These deficiencies and problems are overcome by the present invention.